Method of manufacturing an in-mold laminate component

ABSTRACT

A method is provided for manufacturing a painted plastic component such as painted air bag covers, side cladding or exterior bumpers, which includes a painted film sheet and a one-piece thermoplastic elastomeric structural carrier. A bottom contact surface of the film sheet bonds with a front contact surface of the structural carrier by diffusion between the contact surfaces thereof within a mold cavity of an injection mold separate from the mold cavity of a vacuum mold which is utilized to vacuum-mold the film sheet to form the desired painted plastic component.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 551,517, filed Nov. 1, 1995, entitled “Method OfManufacturing A Painted Vehicle Part.”

TECHNICAL FIELD

[0002] This invention relates to methods of manufacturing painted parts,and in particular to methods of manufacturing painted plastic partsadapted for use on motor vehicles such as air bag covers, side cladding,instrument panel cluster bezels, exterior bumpers, and the like.

BACKGROUND ART

[0003] Typically, plastic parts are painted after they are molded. Thepainting process requires elaborate facilities and consequentlynecessitates large expenses. For instance, significant square footage ofa factory must be dedicated to a clean room environment for the sprayingof paint and clear coat and for the baking and curing of paint oncomponents, such as those components used in the automotive industry,such as body panels, air bag covers, instrument panels and the like.Moreover, solvent-based paints have in recent years raised significantenvironmental concerns because of the volatile organic components whichare emitted into the air during the application of such solvent-basedpaints. As a result, the evaporation of such solvents must be strictlymonitored to satisfy environmental and safety regulations.

[0004] In addition, automotive components, especially interiorautomotive components, are strictly scrutinized following the paintingprocess in order to match or conform the automotive component to thestyling and aesthetic requirements of the associated interior trimproduct. Painting such automotive components following the moldingprocess, raises quality concerns with respect to the color, consistency,and thickness of each individual paint application.

[0005] U.S. Pat. No. 4,902,557, the Rohrbacher reference discloses amethod and apparatus for manufacturing a thermoplastic polyolefincomposite useful as an exterior auto or truck body part.

[0006] U.S. Pat. No. 4,769,100, the Short reference, teaches a method ofapplying a carrier film pre-printed with metallic paint to an automobilebody panel in a vacuum forming process.

[0007] U.S. Pat. No. 4,952,351 and U.S. Pat. No. 5,466,412, the Parkerpatents, teach a method of manufacturing an air bag cover for aninflatable air bag system including a bondable film carrier, which ispainted after the film carrier is molded.

[0008] However, the prior art fails to provide a method of manufacturinga painted component wherein the step of painting the component aftermolding is eliminated and further where the component has the structuralintegrity both in terms of durability and strength to support varyingapplications.

DISCLOSURE OF INVENTION

[0009] An object of the present invention is to provide a method formanufacturing a painted component while addressing paint quality issuessuch as: drips, runs, spits, dry spray, light coverage, gloss, colormatch, contamination and paint adhesion.

[0010] Another object of the present invention is to provide a methodfor manufacturing a painted component and reducing molding scrap due tosplay, flow marks and minor surface imperfections which can becompletely covered.

[0011] Yet still another object of the present invention is to provide amethod of manufacturing a painted component, such as a composite air bagcover, side cladding, and the like, wherein the components haveincreased durability.

[0012] In carrying out the above objects and other objects of thepresent invention a method is provided for manufacturing a paintedplastic component. The method includes the steps of providing a filmsheet having top and bottom surfaces; vacuum molding the film sheet andthe mold cavity to obtain a pre-form; placing the pre-form in a moldcavity of an injection mold having a shape defining the desired plasticcomponent; and injecting a thermoplastic elastomer into the mold cavityof the injection mold to generate a structural carrier for the pre-form,the generation of the structural carrier creating sufficient pressureand heat to bond the structural carrier to the bottom surface of thepre-form to form the molded laminate component.

[0013] Further in carrying out the above objects and other objects ofthe present invention, a method is provided for manufacturing a moldedlaminate automotive component. The method includes the steps ofinserting a film sheet into a vacuum forming station to form the filmsheet into a predetermined automotive component shape to create a formedfilm sheet having top and bottom surfaces, placing the formed film sheetin a mold cavity of an injection mold having a shape defining theautomotive component, and injecting a thermoplastic elastomer into themold cavity of the injection mold, such that the thermoplastic elastomeris in mating contact with the bottom surface of the formed film sheet,to generate a structural carrier for the formed film sheet, thegeneration of the structural carrier creating sufficient pressure andheat to bond the structural carrier to the bottom surface of the formedfilm sheet to form the molded laminate automotive component.

[0014] The above objects and other objects, features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best mode for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0015]FIG. 1 is a front elevational view of one type of air bag coveradapted to be mounted on a side door;

[0016]FIG. 2 is a rear elevational view of the air bag cover depicted inFIG. 1;

[0017]FIG. 3 is a sectional view of the air bag cover of FIG. 1 takenalong lines 3-3;

[0018]FIG. 4 is a schematic view of a conventional injection moldingsystem which may be utilized to make the plastic components of thepresent invention, the system is depicted in an open position with thepre-form placed between two plates of the mold body;

[0019]FIG. 5 is a schematic view of a conventional injection moldingsystem depicted in a closed position, with the pre-form placed betweenthe two plates of mold body; and

[0020]FIG. 6 is a schematic view of a conventional injection moldingsystem depicting the mold cavity with the molten resin injected thereinto form the structural carrier for the pre-form.

BEST MODE FOR CARRYING OUT THE INVENTION

[0021] While the examples and figures provided herein refer toautomotive plastic components, this invention has substantialapplication in other areas and is thus intended to have broader scopethan the cited representative examples. In essence, this invention canbe used with any application calling for a painted plastic component.

[0022] Referring now to the drawing figures, there is illustrated inFIG. 1 a front elevational view of one type of air bag cover, generallyindicated at 10, adapted to be mounted on an automotive side door. Theair bag cover 10 includes a painted one-piece outer layer 12, composedof a film sheet, preferably a pre-painted film sheet, which is vacuummolded in a vacuum mold from a material compatible with the air bag bodyor structural carrier 14, which is preferably injection molded in aninjection mold. The air bag body 14 is preferably composed of athermoplastic elastomer. The elastomer of the air bag body or structuralcarrier 14 should be compatible with the outer layer 12 so that a bottomcontact surface of the outer layer 12, mounts with the front contactsurface of the air bag body 14 by diffusion between the surfaces thereofin the injection mold to prevent the air bag body 14 from separatingfrom the outer layer 12 during use of the air bag cover 10.

[0023] The outer layer 12 is composed of a film sheet that ispre-painted. The film sheet is preferably a polyester sheet such asMylar®, a polyurethane or polycarbonate sheet.

[0024] In the preferred embodiment, the outer layer comprises a filmsheet with the following coatings placed thereon, a layer of acryliccolor in mating contact with the film sheet and a layer ofpolyvinylidine fluoride (PVDF) with an acrylic clear coat to protect thefilm from damage and to provide film elasticity, chemical resistance,stain resistance, weathering and UV protection. In the most preferredembodiment, PVDF comprises 72% of the total film thickness which is 0.2mils.

[0025] The thermoplastic elastomer of the air bag body or structuralcarrier 14 is preferably a thermoplastic elastomer such as athermoplastic polyolefin, thermoplastic urethane, polyester,polycarbonate, a mixture of polycarbonate and ABS(acrylonitrile/butadiene/styrene) or similar material.

[0026] For other automotive applications, the carrier 14 is varied toaccommodate the intended use. Accordingly, for bumper/fasciaapplications, the structural carrier 14 can be selected from at leastthe following materials: lomod®, bexloy® and thermoplastic polyolefin.For cluster bezel applications, the structural carrier 14 can beselected from at least the following materials: ABS (acrylonitrile/butadiene/styrene), a mixture of polycarbonate and ABS, polycarbonate,and polypropylene.

[0027] The durometer and elastic or flex modulus of the materials alsovary depending on the desired stiffness of the component. Typically, thedurometer of the air bag body 14 will be in the range of about 20 ShoreD to 100 Shore D, while the flexural modulus will be in the range ofabout 15,000 to about 400,000 psi. Also, typically, the durometer of theouter layer 12 will be in the range of about 15 Shore A to 100 Shore A.These ranges of course vary depending on the desired plastic componentto be manufactured and are only illustrative of one example.

[0028] As depicted in FIG. 3, a sectional view of the air bag cover ofFIG. 1 taken along lines 3-3, in a manufactured component, the air bagbody or structural carrier 14 supports the outer layer 12 which has apre-painted coating 16 placed thereon, followed by a base coat 18,preferably a layer of acrylic color, and a clear coat 20, preferably anacrylic clear coat and a layer of PVDF.

[0029] Referring now to FIG. 4, there is illustrated a conventionalinjection mold, generally indicated at 22, for making a plasticcomponent pursuant to the present invention.

[0030] Briefly, with an injection molding system there is included aninjection molding machine, having a nozzle, generally indicated at 24,for injecting predetermined amounts or shots of molten resin. Theinjection molding machine includes a hydraulic screw ram which isdisposed in a bore formed in a barrel of the injection molding machine.The ram plasticizes and advances resin towards the nozzle 24. Uponcomplete plasticization of the resin, the screw ram is hydraulicallyadvanced towards threaded portions of the barrel to inject moltenplastic through the nozzle 24, as is well known in the art.

[0031] As depicted in FIG. 4, opposing surfaces of male and female moldparts 26 and 28 respectively define a mold cavity 30.

[0032] As illustrated in FIG. 5, there is a depiction of a one-piecepre-form 32 created from the vacuum molded film sheet which is firstplaced in the mold cavity 30. Thereafter, as depicted in FIG. 6, the airbag body or structural carrier 14 is molded in the plastic injectionmolding system to form a completed unitary laminate plastic component.

[0033] The body of the air bag cover 14 may also be formed fromthermoplastic polyolefin, polycarbonate, tee tpe, sebs tpe, and amixture of polycarbonate and acrylonitrile/butadiene/styrene (ABS). Thecorresponding film sheet 12 must be compatible with the plastic of thebody so that diffusion between contact surfaces occurs. Additionally,the laminate should be compatible with the substrate on which thelaminate is to be adhered. In general, this requirement is achieved byselecting a structural carrier 14 with at least one or more materialscommon to the substrate on which the laminate is to be adhered. As anexample, with a thermoplastic polyolefin substrate, the structuralcarrier should include polypropylene.

[0034] In an alternative embodiment, the mold can be modified to producea plastic component with embossed lettering. This embossed effect isachieved by etching into the mold the desired pattern or letters so thatthe letters have at least a 0.5 mm radius on the edge of the letter, orelse the film will tear and stretch.

[0035] The unique features of the laminate plastic components are 1) astiff inner material to support the intended application; 2) reductionand/or elimination of paint problems such as drips, runs, spits, dryspray, light coverage and gloss and improved color match and paintadhesion; 3) reduced molding scrap due to splay, flow marks and minorsurface imperfections, which can be completely covered; and 4) increaseddurability of the resulting plastic laminate components.

[0036] It should be understood that the film sheet can be positioned inthe injection mold either by way of a pre-form, as described above, orby way of a film roll supply. In this way, one can mold in the color atthe press or mold thereby avoiding a secondary painting operation.

[0037] While the best mode for carrying out the invention has beendescribed in detail, those familiar with the art to which this inventionrelates will recognize various alternative designs and embodiments forpracticing the invention as defined by the following claims.

What is claimed is:
 1. A method of manufacturing a molded plasticcomponent, comprising: providing a film sheet having top and bottomsurfaces, the film sheet being selected from the group consisting ofpolyester, polyurethane and polycarbonate; vacuum molding the film sheetin a mold cavity to obtain a pre-form; placing the pre-form in a moldcavity of an injection mold having a shape defining the desired plasticcomponent; and injecting a thermoplastic elastomer into the mold cavityof the injection mold to generate a structural carrier for the pre-form,the generation of the structural carrier creating sufficient pressureand heat to bond the structural carrier to the bottom surface of thepre-form to form the molded laminate plastic component.
 2. The method ofclaim 1, wherein the thermoplastic elastomer is selected from the groupconsisting of a thermoplastic polyolefin, thermoplastic urethane,polyester, polycarbonate, acrylonitrile/ butadiene/styrene,polypropylene, lomod, bexloy, a mixture ofacrylonitrile/butadiene/styrene and polycarbonate, and mixtures thereof.3. The method of claim 1, wherein the step of injecting a thermoplasticelastomer into the mold cavity occurs in a temperature of 420° F. and ata pressure of 50 psi to 15,000 psi.
 4. The method of claim 1, furthercomprising the step of cutting the pre-form prior to the step ofplacing.
 5. The method of claim 1, wherein the structural carrier has aflexural modulus in the range of 15,000 to 400,000.
 6. The method ofclaim 1, wherein the structural carrier has a durometer in the range of15 Shore D to 100 Shore D.
 7. The method of claim 1, wherein the filmsheet is coated with a layer of acrylic color and polyvinylidinefluoride and an acrylic clear coat layer.
 8. The method of claim 7,wherein the polyvinylidine fluoride comprises more than 50% of the totalthickness of the film sheet.
 9. The method of claim 1, wherein the filmsheet has a total thickness of 0.2 mils.
 10. A method of manufacturing amolded laminate automotive component, comprising: inserting a film sheetinto a vacuum forming station to form the film sheet into apredetermined automotive component shape to create a formed film sheethaving top and bottom surfaces, the film sheet being selected from thegroup consisting of polyester, polyurethane and polycarbonate; placingthe formed film sheet in a mold cavity of an injection mold having ashape defining the automotive component; injecting a thermoplasticelastomer into the mold cavity of the injection mold, such that thethermoplastic elastomer is in mating contact with the bottom surface ofthe formed film sheet, to generate a structural carrier for the formedfilm sheet, the generation of the structural carrier creating sufficientpressure and heat to bond the structural carrier to the bottom surfaceof the formed film sheet to form the molded laminate automotivecomponent.